Numerous mold release sheets have been proposed for facilitating the release of the molded laminated structures from the molds in which they are formed. Such release sheets have included single layer sheets, multilayer sheets and coated sheets. For example, a polypropylene layer on kraft paper or cellophane has been suggested for making floor and wall coverings (U.S. Pat. No. 3,507,733); and aluminum foil kraft paper composites have been disclosed for making embossed laminates (U.S. Pat. No. 3,700,537).
Thermoplastic materials such as Surlyn ionomer resin; Tedlar polyvinyl fluoride material and Mylar polyester material, all du Pont products, have been used or suggested for possible use as release sheets under specific molding conditions (U.S. Pat. No. 3,969,174).
Release sheets with cured coating have also been disclosed (U.S. Pat. No. 4,166,150) and various methods of preparing release sheets published (U.S. Pat. No. 4,243,461; and U.S. Pat. No. 4,263,073).
Mold release sheets have also been proposed for the processing and production of epoxy laminates and multilayered circuit board laminates. For example, the above-mentioned Tedlar product has been used as a release sheet for epoxy multilayered circuit boards.